An OPC UA Server that implements this Companion Specification needs to implement the Glass Base Server Profile (including the Facets Glass Identification Server Facet and Glass Minimal Production Facet). Optional extensions are the Glass Event Server Facet, the Glass Dynamic Production Server Facet and the Changeable JobList Facet. One of the three Job Facets needs to be implemented (Processing, Cutting, Assembly). The following figure shows the structure of the base server profile and facets. The mandatory Profiles are grey, optionally are green and the yellow Profiles are optional and describe the production process. Mostly, only one of the yellow Facets is needed.